There is increasing concern today directed to the high blood lipid levels, especially cholesterol and triglycerides, experienced by a significant proportion of the population. Elevated blood lipids can be indicative of such potentially serious health problems as coronary artery disease. The relationship between blood lipid levels and fat consumption in the diet has been well-studied and extensively documented. Lowering blood lipids to minimize health problems almost always involves modifying the diet to decrease or substantially eliminate fat consumption. As anyone who has ever lived with such dietary restrictions knows well, limiting fat consumption is difficult. The fat content of many foods contributes to their good taste and satisfying mouth feel.
Medical and nutrition experts have discovered that the elimination of all fat from the diet is not necessarily helpful in lowering elevated blood lipid levels and promoting good health. Some fats, in particular, Omega-3 polyunsaturated fatty acids, have been demonstrated to have beneficial effects in reducing the risk of heart disease and other conditions. However, it is recommended by most health experts that not more than 30% of the calories consumed each day be derived from fat. Of the fat calories consumed, at least about 5% of these calories should come from Omega-3 polyunsaturated fatty acids and a like amount from other Omega polyunsaturated fatty acids, specifically Omega-6 polyunsaturated fatty acids. Maintaining a favorable balance between the consumption of Omega-3 and Omega-6 fatty acids appears to be very important. An excess of Omega-6 fatty acids can interfere with the beneficial effects of the Omega-3 fatty acids. The diets of most consumers tend to be higher in Omega-6 fatty acids, in part because Omega-6 fatty acid-containing foods are more readily available and are more palatable. Additionally, some Omega-3 polyunsaturated fatty acids are unstable and easily destroyed.
The oils from land-grown plants and the animals fed on such plants are high in Omega-6 fatty acids, and they form a large part of the average diet. Omega-3 fatty acids are available in comparable amounts from only a small number of land-grown food plants, including walnuts, flax-seed, rapeseed (the source of canola oil) and purslane. The best dietary sources of Omega-3 fatty acids are marine: fatty fish that live in very cold water, including mackerel, anchovies, herring, salmon, sardines, Atlantic sturgeon, tuna and lake trout. These fish contain between about 1,000 and 2,300 milligrams of Omega-3 polyunsaturated fatty acids in about 3 and one-half ounces of raw fish. Other fish are also good sources of Omega-3 fatty acids, however.
Unfortunately, despite the overwhelming evidence of the beneficial health effects to be realized by consuming high Omega-3 polyunsaturated fatty acid-containing fish, a large number of people find it very difficult to do so. Good, fresh fish may not be readily available. Many people, moreover, have never acquired a taste for fish or find it difficult to prepare because of the strong taste and smell which is associated with most fish that is not perfectly fresh. Cleaning fresh fish is a task that many find unpleasant and, as a result, they forego eating the fish they have caught unless they can find someone else to do the job. Consequently, there have been increasing efforts to increase the Omega-3 polyunsaturated fatty acid content of foods which are readily available and which a large number of consumers will prepare and eat.
One food that is appealing to a substantial proportion of the population is eggs, especially eggs from chickens. Eggs are nutritionally balanced, taste good, are easily obtained at reasonable cost and are easy to cook. However, eggs contain somewhat high amounts of cholesterol and other lipids and have been accused of increasing blood cholesterol levels when too many are eaten too often. Therefore, despite the high food value of hens' eggs, many medical practitioners and nutritionists recommend that their high cholesterol patients reduce significantly or eliminate completely this otherwise excellent food. Various egg substitutes with reduced cholesterol and lipids are available. Not only do these substitutes differ in many respects from real eggs, however, but they also do not contain any significant amounts of Omega-3 polyunsaturated fatty acids. Therefore, the beneficial effects derived from the consumption of foods, such as fish, which have high Omega-3 polyunsaturated fatty acid levels are not available with egg substitutes.
Increasing the Omega-3 polyunsaturated fatty acid concentration of poultry products, including eggs has been suggested by the prior art. U.S. Pat. No. 4,918,104 to Weiss et al., for example, describes a method of increasing the concentration of Omega-3 polyunsaturated fatty acids in poultry by administering to the poultry a preformed Omega-3 fatty acid or a metabolic precursor of an Omega-3 fatty acid. The Omega-3 fatty acid or precursor is added in high amounts to a specialty feed composition which is fed to broilers and laying hens. The method described in this patent is stated to produce increased Omega-3 polyunsaturated fatty acid levels in chicken meat and eggs. This result is achieved by a feeding method which feeds the chickens an unbalanced diet for a period of time sufficient to demonstrate an increase in Omega-3 polyunsaturated fatty acids in the meat and eggs. However, the feed composition and feeding method described in this patent are not useful on a commercial scale to produce, consistently, over an extended period of time a large, commercially valuable supply of chicken eggs and meat high in Omega-3 fatty acids.
The Omega-3 fatty acid source preferred in the method of U.S. Pat. No. 4,918,104 is menhaden oil, which imparts a somewhat fishy odor and taste to the poultry products produced according to the method described in this patent. As a result, only those consumers who are accustomed to eating fish are likely to find these products acceptable. Additionally, the feeding of broilers and laying hens the unbalanced diet disclosed in this patent as described is highly likely to lead to problems in the chickens that reduces significantly their commercial value. For example, chickens force fed a diet that is high in Omega-3 polyunsaturated fatty acids exhibit listlessness, molting, lack of appetite, abnormal digestion and weight loss and are generally dull and inactive. Laying hens fed such a diet, moreover, demonstrate reduced egg production. Consequently, the method of increasing Omega-3 polyunsaturated fatty acid levels in poultry eggs disclosed in U.S. Pat. No. 4,918,104 will not produce a sufficiently high egg yield for a commercially viable egg production operation.
The prior art, therefore, does not disclose a commercially useful method for increasing the Omega-3 polyunsaturated fatty acid concentration of eggs and other poultry products that can be used in actual commercial production to successfully produce a dependable commercially significant supply of high Omega-3 fatty acid-containing poultry products.